In order to increase the life of oil or grease lubricated rotating systems that are operated at high temperatures, high speeds, and/or high loads, various additives and thickeners are sometimes added to the bearing lubricants.
It has been found, for example, that some compounds that have a lattice structure are good additives for lubricants. These include the selenides and sulfides of tungsten, molybdenum, tantalum, and niobium. However, it has also been found that compounds that are chemically similar and that also have a lattice structure have a very poor lubricating ability. For example, tellurium is chemically very similar to selenium, but the tellurides of tungsten, molybdenum, tantalum, and niobium are very poor lubricants. Other compounds that have a lattice structure, such as calcium fluoride, are also poor lubricants at temperatures less than about 600.degree. F. Titanium sulfide, which also has a lattice structure, is actually abrasive. Thus, it is difficult to predict from the chemical structure alone whether or not a compound that has a lattice structure will actually perform well as a lubricant.
During extended use, turbine and drive motor main shaft bearings develop electrical pitting damage due to electrical charge build up. To avoid this pitting damage, the charge has to be physically bled via electrical paths from within the internals of the turbine to the frame.
There remains a need for an electrically conductive lubricant capable of bleeding the charge build up in order to prolong the life of the machinery.